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Ocular Motility > B11 > Flashcards

B11 Flashcards

1
Q

Vision condition in which a person can not align both eyes simultaneously under normal conditions

A

Strabismus

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2
Q

Causes of Strabismus?

A

1) Congenital
2) accom ET
3) abnormal visual development
4) Neurological

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3
Q

Important questions to ask:

A

1) Onset?
2) Head trauma?
3) perinatal hx?
4) other neurological signs?
5) old photos?
6) head tilt?

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4
Q

Types of Neurological strabs:

A
  • CN 3, 4, 6 palsies
  • neuro diseases (myasthenia gravis, botulism)
  • post fossa tumors or malformations (Arnold Chiari)
  • raised intracranial pressure (hydrocephalus, idiopathic, tumor)
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5
Q

Strab symptoms:

A
  • diplopia
  • blurred vision
  • reduction in peripheral vision
  • headaches
  • dizziness
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6
Q

Oculomotor Nerve Palsy (CN 3)

Muscles/anatomical structures innervated:

A

SR, MR, IR, IO, sup palpebral levator muscle, Edinger-Westphal nucleus

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7
Q

Eye/head position seen in CN 3 palsy

A

Down & Out

ptosis, dilated pupil with no accom resp

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8
Q

Etiology of CN3 palsy in children

A

Congenital
Vascular (AV malformations)
Primary tumor
Metastatic tumor

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9
Q

Etiology of CN3 palsy in young adults

A

Demyelinating
Vascular (hemorrhagic or infarction)
Tumor

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10
Q

Etiology of CN3 palsy in older adults

A

Vascular (infarct)

Tumor

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11
Q

Ischemic/Vascular CN 3 palsy causes

A

Diabetes
Hypertension
Pupil sparing

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12
Q

Compressing (non-pupil sparing) CN 3 palsy causes

A

Intracranial aneurysm

  • most common sites: Post comm a., ICA, basilar a.
  • risk of rupture causing Subarachnoid heme

Neoplasm

  • primary tumors: neuromas, schwannomas
  • tumors adjacent to nerve: pituitary, sphenoid wing meningioma
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13
Q

Trauma CN 3 palsy causes

A

Severe blows to head w skull fracture and/or loss of consciousness

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14
Q

Migraine CN 3 palsy causes

A

Ophthalmoplegic migraine ->from recurrent demyelinating neuropathy?
( can be seen in children & young adults)

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15
Q

Inflammatory CN 3 palsy causes

A

MS

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16
Q

Infection CN 3 palsy causes

A

Meningitis

Viral

17
Q

Tests to eval CN 3 palsy

A

1) Case hx: diplopia? Decr vision at near? Onset? Trauma?
2) external observation
3) VA
4) CT
5) EOMs
6) pupils
7) NPC
8) accom testing
9) Hess-Lancaster test

18
Q

Trochlear Nerve Palsy (CN 4)

Muscles/ anatomical structures innervated:

A

SO

19
Q

Eye/head position in CN4 palsy:

A

Up & In

Compensatory head TILT to OPPOSITE side of palsy (ex: R head tilt = LSO palsy)

20
Q

CN4 pathway

A

(Longest intracranial pathway & fx is purely somatic motor)

  • exits posteriorly from midbrain & crosses one another
  • partially encircling the midbrain
  • decussates after midbrain
  • runs anteriorly & inferior w/in subarachnoid space before piercing the dura mater adjacent to post clinoid process of sphenoid bone
  • Nerve travels along lateral wall of cavernous sinus (beside CNIII, CNVI, V1 & V2, & ICA) before entering orbit
  • enters orbit via Sup orbital fissure
  • innervated only the Sup Oblique m. of each eye
21
Q

CN 4 Palsy symptoms:

A
  • Vertical diplopia, exacerbated when looking down & in (such as reading or walking down stairs)
  • head tilt away from affected side
22
Q

CN 4 is near the descending sympathetic fibers, thus what can also be present during a CN 4 palsy?

A

Ipisilateral pre-gang. Horner’s Syndrome

Horner’s syndrome triad: miosis, ptosis, anhydrosis

23
Q

Etiologies of CN4 palsy

A

Congenital

  • abnormal development of CN4 nucleus
  • abnormal development of peripheral nerve or tendon

Acquired

  • idiopathic (#1)
  • head trauma w/ loss of consciousness (#2)
  • microvasculopathy (DM, atherosclerosis, HTN)

Others:

  • tumor
  • aneurysm
  • MS
  • Iatrogenic injury
24
Q

Test used to eval CN 4 palsy

A
  • Case hx: vertical diplopia? Difficulty reading? Sense of things are tilted?
  • external obs
  • CT
  • EOMs
  • pupils
  • Parks 3 Step
  • NPC
  • Hess-Lancaster
25
Q

Abducens Nerve Palsy (CN6)

CN 6 innervated what muscles/anatomical structures?

A

LR

26
Q

Eye/head position seen in CN 6 palsy

A

IN

Compensatory head TURN TOWARD affected eye

27
Q

CN ____ has a long external course through cranium making it susceptible to _____________(list 5)

A

6; injury, incr ICP, mastoid infection, skull fracture, tumors

28
Q

Lesion of nerve, root, or nucleus of CN6 presents as

A
  • ipsilateral paresis of LR
  • convergent strabismus incr in temporal gaze
  • lateral diplopia
  • ipsilateral paresis of facial muscles (for nuclear lesions) (CN7 encircles CN6 n.)
29
Q

Most commonly affected oculomotor n. in adults & 2nd most common in children

A

CN6

30
Q

Muscle more affected by ischemia than other EOMs

A

LR

Ocular Motility (1 decks)

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